Pesticides: DDT

1. Pesticides: DDT Tonatiuh Hernandez Bio. 2B

2. What is a Pesticide • Chemical used and created by humans to kill and control undesirable organisms (such as insects or certain plants) • A positive note on pesticides: They allow food producers to increase crop production because they eliminate pests that would otherwise kill crops • A negative note on pesticides: Reproductive problems, links to cancer, and genetic damage are just some of the risks associated with pesticides • The controversy with pesticides lies in the fact that they are useful in an agriculture or disease prevention setting, but they are also known to be a major health risk

3. What is DDT? • One of the most commonly used and well known pesticides in the world. • It was created in a laboratory in 1873 and it’s scientific name is dichlorodiphenyltrichloethane. • It is created by the reaction of trichloromethanal with chlorobenzene • The Chemical formula for DDT is C14H9Cl5. • In it’s pure natural form, DDT is a white crystalline powder with minimal odor.

4. History of DDT • Created in a Laboratory in 1873 • 1939, Dr. Paul Muller discovered DDT also effective in killing insects • During WWII, DDT used to kill mosquitoes that spread malaria and other insect-borne human diseases among civilians and the military • After the war, DDT was commercialized and accessible to the public • The U.S. used and produced millions of pounds of DDT during the mid 1900’s • In 1972, the EPA banned the sale of DDT for use on crops • The U.S. no longer uses DDT, but many other countries in the world continue to use it to control malaria (as in the tropics) or other insect-borne human diseases

5. Applications • Used to kill agricultural pests that destroy or harm crops • Used to control the spread of deadly diseases carried by insects

6. Dangers of DDT • DDT does not break down in the environment or in living organisms • It has a long life span, which is due to its high solubility in fat and low solubility in water • High solubility in fat means that the DDT will secrete in the fat of an animal or person and stay there • Since it is stored in the fat of an organism, it can be easily passed down through the food chain

7. How DDT Enters the Body and How it Works • DDT cannot enter the body through the skin, but instead through mucus secretions and through the mouth • Once inside the body, DDT is secreted into the gastrointestinal tract • DDT works by entering a cell through its plasma membrane

8. How DDT Enters the Body and How it Works • Since the plasma membrane is made up of mostly lipids, DDT easily dissolves into it • The problem with the way DDT gets into the cell is that it leaves the membrane open, which causes the cell to leak. • Two very crucial things that leak out of the cell are sodium and potassium ions • The concentration of these two ions inside and outside of the cell are important in determining when the nerve cell will fire its signals • Once in the plasma membrane, DDT does not allow nerve impulses to fire when they are supposed to • When an organism is poisoned with DDT it dies by either convulsions or paralysis

9. Effects of DDT on Animals and Small Organisms • DDT can affect the growth of an organism as small as a microorganism • Causes many problems in fish by disrupting important biological processes • Causes problems in birds by damaging reproductive enzymes that determine crucial biological processes

10. DDT and its Effects on Humans • 1960’s concern for the safety of humans and exposure to DDT • Late 60’s, study showed .025 milligrams of DDT consumed by Americans daily and much higher concentrations for farm workers • How much DDT a person’s body can tolerate determined by their body weight • Anything above 236 mg of DDT per kg of body weight is deadly • DDT is stored in fatty organs, such as the adrenals, testes, thyroid, and at a lower concentration in the liver and kidneys • Milk production depends largely on stored body fat and DDT is absorbed into fat very easily, DDT can be transferred to babies through breast milk • Concentrations of 6-10 mg/kg leads to headaches, nausea, vomiting, confusion, and tremors.

11. DDT and its Effects on Humans • DDT is also an estrogen mimic • An estrogen mimic is a molecule that attaches itself to an estrogen receptor in a cell and mimics the action of the body's natural estrogen • A decrease in men's sperm counts since the mid 1940's and a rise in the number of cases of endometriosis in woman are being studied to determine whether there is a link to DDT

12. DDT’s Effect on the Environment • DDT's breakdown product is DDTr • Since DDT is fat soluble, water does not wash it away and it remains in the soil where crops were once treated with DDT • DDT can still be detected in water years after it was introduced into a stream or lake • Land that contains DDTr remnants cannot be used for planting crops without danger of food contamination

13. “Silent Spring” • Book written by Rachel Carson in 1962 • Addressed the dangers of DDT to the public • She stated in her book that DDT was one of many "biocides" to imply that they were killing everything living • Carson’s book provoked interest in President Kennedy who, as a result, created the Life Science Panel to protect the environment from pesticides such as DDT • “Silent Spring” helped spark the growing anti-chemical and anti-pesticide movements during the 1960s, which led to the banning of DDT in the U.S.

14. The controversy surrounding whether DDT is a Carcinogen? • There is evidence that supports that DDT is a carcinogen • Despite evidence, still people trying to prove DDT is not a carcinogen • 1960’s, the National Academy of Sciences, American Medical Association, U.S. Surgeon General, World Health Organization, and the Food and Agriculture Organizations of the United Nations supported the use of DDT • In 1972 the Environmental Protection Agency (EPA) challenged the use of DDT in court, but the judge determined that DDT was not a carcinogen • Soon after the court decision, director of the EPA declared DDT a potential human carcinogen and it was banned • Further studies related to DDT, such as one reported in the New England Journal of Medicine on breast cancer, stated that the evidence of DDT causing breast cancer was not very compelling • Yet, further research has related DDT to birth defects, but since its immediate effect on combating malaria has been successful, DDT is still used in other countries, ignoring the harmful effects on humans and the environment

15. What World Leaders are Doing About This Problem • The international community has agreed on eventually eliminating the use of DDT in the fight against malaria • World leaders have also called upon financial institutions to work towards efforts to develop other strategies for combating malaria and other insect borne diseases without the use of harmful chemical products

16. How to Eliminate DDT? • Because of its sustainability, DDT may never be completely eliminated from the environment • Although DDT may never be completely eliminated, a new CO2 cleaning process is successfully reducing the amounts of DDT in the environment • Under extreme temperature and pressure, CO2 is capable of working as a solvent for DDT in soil • The unfortunate reality of this new technology is the cost, which may prevent it from being used to its fullest potential

17. Work Cited • http://www.oneworld.net/article/view/110927/1/ddt.cfm • http://www.chem.duke.edu/~jds/cruise_chem/pest/pest1.html • http://www.epa.gov/history/topics/ddt/01.htm • www.cdpr.ca.gov • ehp.niehs.nih.gov/qa/105-8forum/forum.html